Mechanical ventilator apparatus and related hardware have long been used in the medical profession for assisting or controlling pulmonary ventilation in situations where the patient requires endotracheal intubation. Intubation is indicated in patients who are unable to spontaneously maintain adequate arterial blood gas values secondary to inadequate respiratory pattern or volumes. This deficit is attributable to a neurological, pulmonary and/or cardiovascular insult, injury or disease process. For example, U.S. Pat. Nos. 3,683,655; 4,397,306; and 4,815,452 illustrate various systems and apparatus used to control and/or assist ventilation. In addition, the assistance of an increase in blood flow from the liver to the heart is required for the purpose of post-operatively maintaining or attempting to obtain better patient blood pressure following some post-operative cardiac procedures. In the Fontan Procedure, in which the patient has no functional right atrium or right ventricle, another goal is to overcome the increased pulmonary vascular resistance to systemic blood flow which in turn, increases oxygenation. In application, various devices such as inflatable bladders and assemblies are sometimes wrapped around the abdominal area. These sometimes are referred to as "pneumobelts". The above-mentioned U.S. Pat. Nos. 3,683,655 and 4,397,306 also illustrate the use of inflatable devices of this type.
A common problem associated with the combined use of two ventilators to simultaneously drive the device described above and to ventilate the patient via an endotracheal tube is that the cycling of these devices is not properly coordinated to provide for maximum efficiency and maximum blood return to the heart and thoracic vessels.
The particular object of the present invention is to utilize the liver's blood reservoir-like properties as a voluminous source to provide additional thoracic blood return which will assist in maintaining an adequate blood pressure and pulmonary circulation in the patient. It is, therefore, an object of the present invention to overcome the disadvantages associated with the prior art referred to above.
Another object of the present invention is to provide an improved system and method wherein the combination of two ventilators used in conjunction with an endotracheal tube and pneumobelt are coordinated so that they work efficiently in tandem in order to obtain improved results in the arterial blood gas values, and maximum possible blood return to the thoracic cavity.